Experiencing a familiar concept implicitly activates related concepts. This activation processes. However, as the project has shown, such activation also affect memory for direct experience. The goal of this research is to understand how implicitly activated concepts affect the encoding and retrieval of direct experience and to develop a theoretical model that explains this influence. The working model assumes that the encoding of related concepts incorporates them into the learning or testing episode, and that such 'Incorporation can either facilitate of hinder depending on the tasks that must be performed. The model specifies when related concepts are likely to be encoded and how they affect performance. The methodology requires subjects to encode familiar concepts under various learning conditions and to retrieve these concepts under various testing conditions. Variations in learning conditions include manipulations of context, encoding orientation, timing and interference; variations in testing conditions include manipulations of type of retention test, the nature of the retrieval cues and location of testing. All experiments involve manipulations of the number of related concepts activated by directly experienced concepts. In general, concepts that activate larger networks of related concepts are not as likely to be remembered, nor are they as likely to be effective as retrieval cues. These findings hold for both phonemically and meaning- fully related concepts. Implicitly activated concepts can interfere with memory for what was actually experienced. However, there are exceptions to these general patterns, even reversals of effect, and they help explain how implicitly activated concepts affect behavior. Findings will be relevant to understanding memory in normals, and will have direct implications for research in perception, learning, speech, reading, language comprehension, and for practitioners in mental health who rely on cues to help clients retrieve information.